Workshop › Asteroids › Step 6 of 41

Turning

What we are doing

Every frame, update will change the game a little. First job: while left is held the angle gets smaller (turn left), while right is held it gets bigger (turn right), by TURN radians per frame.

```js
const TURN = 0.07 // radians per frame

function update() {
  if (keys.ArrowLeft) ship.angle -= TURN
  if (keys.ArrowRight) ship.angle += TURN
}
```

What it means

• ship.angle -= TURN takes 0.07 from the angle, += adds it.
• Both ifs are checked every time, so holding both keys cancels out.

Your turn

1. Under SHIP_R write TURN.
2. Above function drawShip() { write update, followed by an empty line.

Skills: Keyboard and mouse input

← Which keys are down? The game loop →

All steps

1. Black space
2. Where the ship is
3. Which way it points
4. A triangle ship
5. Which keys are down?
6. Turning
7. The game loop
8. Thrust and drift
9. A little friction
10. A speed limit
11. Around the screen
12. Making a bullet
13. Fire!
14. Bullets fly
15. A lifetime for bullets
16. Making a rock
17. Four big rocks
18. Drawing the rocks
19. Jagged rocks
20. Drifting rocks
21. When do two circles touch?
22. Breaking a rock
23. Bullets hit rocks
24. Points
25. Show the score
26. Losing a life
27. A rock hits the ship
28. Show the lives
29. What time is it?
30. A moment of safety
31. Blink while safe
32. Waves of rocks
33. The next wave
34. Faster every wave
35. One function to start
36. Playing or over
37. Game over
38. Best score
39. GAME OVER
40. Play again
41. Build it yourself: hyperspace